Sunday, February 12, 2006

A thoughtful reader of my previous post, Lobster Boil: The Curious Response to Global Warming's Arrival, emailed a minor objection that some places such as Minnesota (which I mentioned in the piece) are likely to benefit from global warming. He claimed the state will have milder weather and by extension a longer, warmer growing season. Farmers might have to plant different crops, but maybe not.

For Minnesota, alas, not all modellers predict this benign outcome. One model suggests that Minnesota and indeed most of the continental United States will experience increasingly frequent and prolonged droughts. The modelling was the work of David Rind of the Goddard Institute for Space Studies. Rind concluded that climate change models underestimate the intensification of drought because they do not have detailed enough models of land surfaces. His rather troubling conclusions were discussed recently in The New Yorker magazine's "Climate of Man" series.

While global warming is now an accepted fact and human activities, particularly the burning of fossil fuels, are almost certainly the most prominent driver, the future course of that warming remains highly uncertain. Global warming models are exquisitely sensitive to assumptions about future emissions of greenhouse gasses which are, in turn, linked to population growth, economic activity, the use of renewable energy sources, and advances in technology that might mitigate such emissions.

Even more uncertain than the general course of global warming are effects on specific areas. Minnesota may seem more like Missouri and Arkansas by the end of this century, or it may seem more like the Mohave Desert. The issue of water is especially critical in assessing whether there will be any "winners" from global warming. Some places may get more rainfall, but at the wrong time. For instance, snowmelt runoff will decrease in many places significantly as snowfall increasingly turns to rain in winter. That means more runoff in winter and less in the spring and summer when it is more likely to be needed for irrigation and other purposes.

Rind also points to the the problem of adaptation. This is because global warming is a moving target. Minnesota will not suddenly warm to the balmy temperature of St. Louis and stop. Instead, the state will get there in steps with warming every decade that will bring new challenges for adaptation every few years. And, Minnesota and other places won't stop warming at the end of the century. On current projections, the world will keep getting warmer for a long time after that. Here is what Rind told The New Yorker:

“I gave a talk based on these drought indices out in California to water-resource managers,” Rind told me. “And they said, ‘Well, if that happens, forget it.’ There’s just no way they could deal with that.”

He went on, “Obviously, if you get drought indices like these, there’s no adaptation that’s possible. But let’s say it’s not that severe. What adaptation are we talking about? Adaptation in 2020? Adaptation in 2040? Adaptation in 2060? Because the way the models project this, as global warming gets going, once you’ve adapted to one decade you’re going to have to change everything the next decade.

“We may say that we’re more technologically able than earlier societies. But one thing about climate change is it’s potentially geopolitically destabilizing. And we’re not only more technologically able; we’re more technologically able destructively as well. I think it’s impossible to predict what will happen. I guess - though I won’t be around to see it - I wouldn’t be shocked to find out that by 2100 most things were destroyed.” He paused. “That’s sort of an extreme view.”

Rind admits, of course, that his models are not reality, just projections. But, precisely because of the uncertainty in modeling that far into the future, we should be cautious about accepting the notion that we can define future "winners" and "losers" as a result of global warming. Indeed, those who turn out to be "winners" may find themselves inundated by migrants from areas that end up "losers" because of the rise in sea-level (or disasters associated with that rise), droughts and floods, and agricultural devastation.

Without having to accept Lovelock's fatal diagnosis, one can at least acknowledge that he is reminding us that we are all in this together. To imagine that global warming is a game with "winners" and "losers" may be the surest way to make losers of us all.